Fuel systems for gas turbine engines



Feb. 18, 1969 o. N. LAWRENCE 3,427,804

FUEL SYSTEMS FOR GAS TURBINE ENGINES Filed March 17, 1967 Sheet of- 2 Feb. 18, 1969 o. N. LAWRENCE FUEL SYSTEMS FOR GAS TURBINE ENGINES Sheet Filed March 17, 1967 O Patented orifice 23 in the plunger 22 and this fuel can escape 3,427,804 through a passage 25 under the control of a valve 27 and FUEL SYTEMS FOR GAS TURBINE ENGINES thence through an outlet pipe 26 to the pump inlet or g i fi Lawrenge f. h h. g$ the reservoir 11 in the system. The rate of flow through fig (In les) e g 5 the restricted orifice 23 is dependent upon the pressure Filed Mar- 17, 1967, Ser. No. 624,017 difference across the plunger 22 which is dependent in U5, (3], 0-39, 1 Claim turn upon the position of the plunger 22 in the cylinder 28 Int. Cl. F02g 3/00; F02c 9/08; G05g 11 /00 ABSTRACT OF THE DISCLOSURE A gas turbine engine fuel system having a pump supplying fuel through a passage to the engine, a plunger for controlling flow, a lever connected to the plunger and controlled by a mechanical mechanism responsive to at least 15 two parameters related to engine conditions.

The valve 27 is a half ball carried at one end of a lever 28, the opposite end of which is pivoted at 30 to a suitable structure 29 in which the cylinder 18 is formed. Near the first position 30 the lever 28 has connected to it a tension spring 31 the other end of which is connected to a rod 32 on the plunger 22.

A further spring 33 connected at the same position to the lever 28 is adjustable to determine the force which the spring 31 can exert upon the plunger 22. I Near the end of the lever 28 carrying the half ball of This invention relates to fuel systems for supplying fuel 'f valve there is disposed a mechanical meehahism to gas turbine engines, such a system being under manual lnustrated FIGURE 2 and to be more fully deserlbed,

control and being arranged to maintain a set engine speed this mechanism havlrfg roller bearing against the despite changes in certain functions such as, for example, lever The mechamsm 1S capable of being actuated by pressures obtaining in various regions in the engines and a lever 35 or by an arm 36 to cause movement of the engine Speed fluctuatione lever 28 and thus to cause movement of the plunger 22 The object of the invention is to provide a fuel system to control the flow rate of fuel through the passage to the of the type referred to in a convenient and effective form. engme- Movement of the lever 23 changes the opening In accordance with the present invention a fuel System of the valve 27, which in turn enables a new equilibrium for a gas turbine engine comprises a fuel supply pump, a

position for the plunger 22 to be established with a new passage through which fuel can flow between the p pressure difference value across the plunger 22.

and an ehgme with which the system 18 associated a Actuation of the lever 35, which is pivoted in the struc plunger, the position of which determines the rate of how tum 29 P 37 so that its e remote from h roller f f l through the passage, a lever connected to the extends into a chamber 38 in the structure 29, 15 by mean phmger to impart movement thereto, and a mechanical which are responsive to changes in the pressure ditferenc mechanism engageable with the lever and being responbetween the preemies upstream and dewhstfeiilm It sive to changes in at least two parameters related to en- Spectwely of the engme compressore level 35 15 e0! gine conditions to cause movement of the lever. nected by a rod 40 to the Centre a d1aPhfagm 1 an The invention will now he described by way of exam also to an evacuated bellows 42 within the chamber 3 pte, with reference to the accompanying drawings in This chamber 38 is sub ected to the air pressure upstrea: of the engine compressor through the pipe 43 and th which: FIGURE 1 is a diagrammatic representation of a fuel 40 Porno of h chember 38 whlehls enclosed y the d1 system in accordance with the present invention and Phragm 41 Subleeted to a hmehoh of the Pressures 11 stream and downstream of the compressor, this functi being obtained by an air potentiometer formed by a p of restrictors 44, 45, the former being in the pipe 43 a FIGURE 2 is a perspective view of a mechanical mechanism forming part of the system in FIGURE 1.

The system shown is for use in supplying liquid fuel to a gas turbine engine 10 and is provided with a reserthe latter bemg a P 46 subleeted t0 the p voh 11 for storing fuel which can be delivered by a pump downstream pressure. Changes in these pressures t] of the vary the position of the lever 35 which, in turn acts u] 12 to burners 13 in the engine. The pump 12 is Swash plate type and the Stroke is controlled by a Serve, the roller 34 to alter the position of the lever 28 in a m ner to be described.

mechanism 14 which is itself influenced by the pressure at the outlet of the pump 12, in a pipe 15 and also by the A Second Parameter for determining h PP I H of pressure of fuel downstream of a speed responsive conlever thus e h w Ihe ehglhe 1S determl trol, to be more fully described, this pressure being exby engme P Thls 1S hPP t the mechanism rt erted on the servo mechanism 14 through a pipe 16. Fuel 34 through the 36 pivoted 0n the flt ture 29 a1 fl to the burners 13 i use normally takes place an extension of this arm 36 at the other side of the I through a passage formed by an outlet pipe 17 from the 47 engaging a member The member 43 1S n Pump 12, a cylinder 18 a pipe 19 leading to the Speed by a spring 49 and its permitted travel is determine responsive device and a pipe 20 leading from the speed two smps 50,51 m h Structure The member 48 is acted upon by weights 53 moi responsive device to the burners 13 in the engine 10. The Z1 o tesuppyo ue o eengine.

The cylinder 18 contains a plunger 22 having a rednven by the engme through gearmg mdleeted at 5 stricted orifice 23, the plungei: position determining the 7' d h 1 h rate of flow of fuel from the pipe 17 into the cylinder 18, f t comm f e Poslhoh of the al and thence to the pipe 19. The cylinder wall for this purgg f meehamsm to h the P pose has a plurality of orifices 24 or a shaped opening, a o g 1;. t u z g el the.welghts p change in flow through the orifices 24 caused by movemem 18 con to e Y lf 49 Whleh e1 mien; of the plunger being proportional to the magnitude iai l gg el zl ighh g n g tgd th l g hl'i 'l 3 0 t at movement, 1S 0 6C 2. ever 6 a CI The position of the plunger 22 is maintained by fuel under the control of the Pilot pressure above and below it (as seen in the drawing) there To the shaft 54 is also connected a second car: being ma tamed a pressure above it through the restricted with weights 62 which are lighter than the weights which are arranged to act upon a sleeve 63 in which is the mechanism about the shafts 71. When the mechanism formed a triangular or other shaped orifice 64 through is in the position illustrated, the movement of the arm which fuel must pass between the pipe 19 and the pipe 20. 36 has no effect upon the lever 28 but in any other posi- This device is thus also speed responsive and the engine tion, the roller 34 is moved and there is a consequential speed determines the position of the sleeve 63 and thus movement of the lever 28 thus altering the fuel flow rate the area of the triangular orifice 64 which is exposed for a to t e engine. the flow of fuel the orifice being arranged to be partially 'It is to be understood that other forms of mechanical blanked off by a metering edge 65 in the structure 29 in mechanism performing the same function can be utilised which the sleeve 63 is axially slidable. The sleeve 63 is Having thus described my invention what I claim as mounted in a cylinder 73 the end of which remote from new and desire to secure by Letters Patent is: the weights 62 is in communication through a pipe 74 1. A fuel system for a gas turbine engine comprising a with the pump outlet pipe 17 There is thus applied to the fuel supply pump, a passage through which fuel can flow sleeve 63 a pressure acting in opposition to a force, the between the pump and an engine with which the system value of which is determined by engine speed applied by is associated, a plunger, the position of which determines the weights 62. Any out of balance of these forces moves the rate of flow of fuel through the passage a lever conthe sleeve 63 to control the quantity of fuel to the engine nected to the plunger to impart movement thereto and a through the orifices 64. ny change in the flow of fuel mechanical mechanism engageable by the lever the methrough the orifice 64 results in a change in pressure in chanical mechanism comprising a first part connected for the pipe and thus in the pipe 16 which communicates angular movement about an axis to means responsive to with the servo mechanism 14 for varying the pump stroke 20 changes in one parameter related to engine conditions, a and hence fuel supply to the engine In this ma e the further part connected to the first part for angular movepressure drop across the orifices 24 is maintained at a value n relatlvely t0 h fi P t a ut an aX S fft, ut determined by engine speed. parallel, to that about which the first part is movable, a Referring now to the form of the me hani al me hafurther lever connected to means responsive to changes nism, this is shown in FIGURE 2 and comprises th oll- 25 in another parameter related to engine conditions, said er 34 against which the lever 28 bears, the lever 35 also further lever acting in One dire o 0 1 Said further P bearing against it at right angles to the line action of the and 531d lever Connected to the Plunger engaglng With the lever 28 The roller 34 1s a multrple one d 1s suspended further part of the mechanism in a direction transverse for rotation on an axle 66 which, in turn is carried by a With respect to the direction of action of the further pair of arms 67 which, at their opposite ends are conlever 011 Said further P nected to a second pair of arms 68 through coaxial shafts 69. The second pair of arms 68 are joined by a bar 70 References Cited and are connected to coaxial shafts 71 rotatably mounted UNITED STATES PATENTS in the relatively fixed structure 29. The axle 66 can swing about an arc with its centre on the common axis of the j u hafts 69 this are at one point being coincident with the 3142259 7/1964 :ommon axis of the shafts 71, this position being shown. y er 6O 39'28 XR As seen it; FIGURE 1, the mechanism is slightly ditfer- 333OIO9 7/1967 Cams al 604918 nt but similar parts having been indicated by like nuierals and furthermore it will be seen that one of the arms JULIUS E. WEST Pnmary Exammer' 8 has forks 72 in which the end of the arm 36 engages. U5, C1, X,R Thus in use, the position of the roller 34 can be altered 74 479 

